Fixing Climate

Written by Wallace Broecker and Robert Kunzig, Fixing Climate: What Past Climate Changes Reveal about the Current Threat – And How to Counter It combines relatively conventional thinking about the nature and consequences of climate change with a rather unusual solution. It is rich in personal anecdotes, but feels a bit as though it lacks overall rigour.

Climatic history

Much like Richard Alley’s Two Mile Time Machine, this book discusses how various types of natural record can inform scientists about the past state of the climate. These include core samples of ice, mud, and sediment. They also include fossils, living trees, and much else.

This book tells a number of interesting stories about how some of this data has been collected and analyzed, as well as about the personalities of those who did the work. It highlights those areas in which there is a good level of understanding, those where there are competing theories, and those where present theories have not yet proved adequate for explanation.

The two big points made are that climate is unstable and sometimes prone to big abrupt shifts and that human emissions of greenhouse gasses (GHG) are ‘poking the ill-tempered beast with a sharp stick.’

Likely consequences

Broecker’s book claims that the two most plausible threats from climate change are sea level rise – from melting ice in Greenland and West Antarctica – and droughts induced by changes in wind patters and precipitation. It also mentions the possibility of a thermohaline circulation collapse.

The book does not contemplate truly catastrophic runaway climate change scenarios, in which the full potential of burning tropical forests and melting permafrost is brought to bear. Instead, it restrains itself to the possibility of a 14 metre sea level rise – possibly over centuries – and the emergence of very profound droughts in some areas that extend for hundreds of years.

The book highlights how there are big uncertainties about the timing of changes, but asserts strongly that prompt and extensive mitigation action is required.

What is to be done?

Where Monbiot and Romm have detailed plans for emission reductions through different wedges, Broecker asserts that the best mechanism for dealing with rising atmospheric GHG concentrations is to do as follows:

Use a huge number of machines to absorb carbon dioxide (CO2) directly from the air.

Store it temporarily in a chemical compound.

Separate the compound from the CO2, recycling the former for re-use in the machines.

Bury the CO2. This can be done in the deep ocean (delaying emissions from right now until later, ‘shaving the peak’ of the concentration rise), in old oil and gas fields, or in saline aquifers.

At the same time:

Dig up enormous quantities of carbon absorbing ultramafic rock.

Grind these to fine powder.

Let them absorb atmospheric CO2

Dump the carbon-bonded rock somewhere

At the same time, emissions from fixed sources like power plants should be captured and stored. With this combination of activities, the authors assert, we could reduce the global concentration of GHGs to whatever level we prefer.

This scheme strikes me as very impractical. Every chemical step can be accomplished, but the matters of scale and energy make me doubt whether this could ever be used on a global level. Broecker assumes that our total emissions will continue to grow, from the present level of about 29 gigatonnes. The sustainable level is about 5 gigatonnes, so we would need to deploy an enormous array of capture stations, provide them with carbon-absorbing chemicals, process those chemicals once they are exposed, return them to the machines, and bury the CO2. Even if it would be technically possible to do all this, it is not at all clear that doing so would be cheaper or easier than cutting down on total energy usage, while also investing in the development and deployment of renewable power.

Even if climate change could be addressed, a society built on fossil fuels cannot last. The scheme basically assumes unlimited access to hydrocarbon energy, combined with very limited potential for renewables. To explain why, think about the energy chains involved. Broecker repeatedly asserts that it will take only a fraction of the energy from a set quantity of hydrocarbons to absorb and sequester the resultant GHGs. He basically assumes that we will have cheap coal at least for the foreseeable future. There is reason to doubt this. While we will not exhaust oil, gas, or coal by the end of the century, we may approach or pass the point where it takes as much energy to extract and process as it contains. In that case, we would need renewables regardless of whether we had capture capabilities or not.

In the end, the book is a relatively interesting one. If you want detailed information on paleoclimatology, Alley’s book is probably a better choice. If you are looking for relatively practical solutions to the climate change problem, Romm and Monbiot are probably better bets. That being said, reading this book will definitely inject a few new ideas into your thinking about climate, climate science, and how humanity is to respond. It is also worth noting that it is possible that capturing CO2 straight from the air will prove viable in terms of energy and economics. If so, we should see firms starting to do it pretty soon after a decent carbon price is imposed in developed states.

We need something that can be manufactured, like air conditioners or cars, by the millions. Each day, a unit would take about a ton of CO2 out of the atmosphere, liquefy it and send it out through pipes to wherever it’s going to be stored. The developers are now envisioning a device about 6 to 10 feet in diameter, 50 feet high. It would be like a little silo, in that shape so the wind could blow through it from any direction.

Broecker said, “a leveling off atmospheric CO2 at between 550 and 650 ppm is within our power.”

The project would not come cheap. Broecker estimated that it could take $600 billion a year to reduce the global concentrations by as much as a half over time. Of course, the estimates of what a failure to act would cost come in at much higher, according to the Nicolas Stern report, perhaps as much as an astronomical 20% of global GDP.

With CO2 rising at a rate of 2 ppm a year it will only take 35 years to eclipse all known CO2 records. “We’re changing things on a decade time scale”, said Broecker, “if we get to 900 ppm we’ll change the entire ecology of the planet.” The panel agreed that we’ll have to employ every technique that we now have to forestall a catastrophe.

Over the last few years the Climate Modeling and Diagnostic Group within the Ocean and Climate Physics Division has conducted an intensive research program on the causes of hydroclimate variability and change over southwestern North America with a particular focus on persistent, multiyear, droughts.

Wallace Broecker is not as important as the other authors, but he is well-known in the surprisingly gripping field of palaeoclimatology. He has spent his career investigating the climate in prehistoric times and, in particular, the role that the oceans have played in the way it changed.

His book is the oddest, and the nicest, of the bunch. He is clearly a rather delightful man, with a penchant for practical jokes; through his life-story, the book explains how scientists have come to understand the history of the world’s climate. That helps illuminate the future. Knowing that sea levels have varied by more than 100 metres in the past, as ice-sheets have melted and re-formed, lends a certain weight to the argument that serious climate change is best avoided.

In this case the presence of a co-writer adds to the charm of the story, for Robert Kunzig seems to have fallen for Mr Broecker and his world. It is easy to see why. Palaeoclimatology is full of people obsessing about fabulously obscure wrinkles in the climate’s history, and investigating them by drilling cores thousands of metres into the Arctic ice, or counting the oxygen atoms in minuscule foraminifer shells to learn just when the world froze and warmed: “the planet in a grain of sand”, says Mr Kunzig, who has a lovely appreciation of the poetry of science.

“Samson has a different idea. Instead of burning fossil fuels to make switchgrass into a liquid, why not just burn the switchgrass?

At REAP’s farm and research facility in Ste-Anne-de-Belleville, Quebec, they cut the switchgrass down in November, just before it snows, then harvest it in April after the snow has melted away. The winter dries the plant enough so that it just has to be compressed into fuel pellets.”

I expect that biomass will be an increasingly important source of energy. Whether switchgrass is the most efficient source or not, I really know nothing about.

Environmental scientist Wallace Broecker proposes that the only way to fix global warming is by literally scrubbing CO2 from the atmosphere and burying it. A professor at Columbia University, Broecker’s written a new book on the subject appropriately titled Fixing Climate. He’s also working with a company called Global Research Technologies to develop machines that would remove CO2 from the air on a massive scale. In the new issue of Smithsonian, Broecker talks about why these devices are our best hope. From the interview:

It is also worth noting that it is possible that capturing CO2 straight from the air will prove viable in terms of energy and economics. If so, we should see firms starting to do it pretty soon after a decent carbon price is imposed in developed states.

This is more or less right, provided the actual technologies for capture and storage won’t cost that much to develop.

Still, I doubt anyone will be able to build a machine that is more economically effective than the fastest growing forms of biomass.

Canadian scientists have created a device that efficiently removes CO2 from the atmosphere. “The proposed air capture system differs from existing carbon capture and storage technology … while CCS involves installing equipment at, say, a coal-fired power plant to capture CO2 produced during the coal-burning process, … air capture machines will be able to literally remove the CO2 present in ambient air everywhere. [The team used] … a custom-built tower to capture CO2 directly from the air while requiring less than 100 kilowatt-hours of electricity per tonne of carbon dioxide.”

Mar 5th 2009
From The Economist print edition
Environment: Removing carbon dioxide directly from the atmosphere could help combat climate change. Will it really work?

PREVENTING catastrophic climate change, most people agree, will mean reducing the level of man-made carbon dioxide (CO2) in the atmosphere. That, in turn, will require the widespread use of “low carbon” technologies such as solar and wind power, more energy-efficient buildings, and so on. Some countries have pledged to reduce their greenhouse-gas emissions by 80% by 2050, and campaigners are calling for cuts of 90% or even 100%. New Zealand, Costa Rica and Norway are racing to become the world’s first “carbon neutral” country. But some researchers think there might be a simpler way to reduce the level of CO2 in the atmosphere: to build “air capture” machines that, as their name suggests, grab it from the air.

“One way in which air capture and renewable energy might fit together well, however, would be to divert excess power from wind farms to air-capture systems. Wind farms sometimes produce more power than utilities can use, particularly if it gets windy at night, when electricity demand is low. Some utilities turn off their wind turbines to avoid overloading their grids. Dr Lackner suggests diverting it instead to air-capture systems. In theory, air-capture systems could then operate at a profit, by generating carbon offsets that could be sold on carbon-trading markets. Dr Lackner even suggests selling such offsets at petrol stations, along with fuel.”